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Message-ID: <20160817082034.GA11837@dhcp-128-65.nay.redhat.com>
Date: Wed, 17 Aug 2016 16:20:34 +0800
From: Dave Young <dyoung@...hat.com>
To: Xunlei Pang <xlpang@...hat.com>
Cc: linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
akpm@...ux-foundation.org, ebiederm@...ssion.com,
Vivek Goyal <vgoyal@...hat.com>, Baoquan He <bhe@...hat.com>,
yinghai@...nel.org
Subject: Re: [PATCH v2 1/2] kexec: Introduce
"/sys/kernel/kexec_crash_low_size"
On 08/17/16 at 09:50am, Xunlei Pang wrote:
> "/sys/kernel/kexec_crash_size" only handles crashk_res, it
> is fine in most cases, but sometimes we have crashk_low_res.
> For example, when "crashkernel=size[KMG],high" combined with
> "crashkernel=size[KMG],low" is used for 64-bit x86.
>
> Like crashk_res, we introduce the corresponding sysfs file
> "/sys/kernel/kexec_crash_low_size" for crashk_low_res.
>
> So, the exact total reserved memory is the sum of the two.
>
> crashk_low_res can also be shrunk via this new interface,
> and users should be aware of what they are doing.
Cc Yinghai Lu for review since he introduced the ,high and ,low logic.
>
> Suggested-by: Dave Young <dyoung@...hat.com>
> Signed-off-by: Xunlei Pang <xlpang@...hat.com>
> ---
> include/linux/kexec.h | 4 ++--
> kernel/kexec_core.c | 23 ++++++++++++-----------
> kernel/ksysfs.c | 25 +++++++++++++++++++++++--
> 3 files changed, 37 insertions(+), 15 deletions(-)
>
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index d743777..4f271fc 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -304,8 +304,8 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
> unsigned long long *crash_size, unsigned long long *crash_base);
> int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
> unsigned long long *crash_size, unsigned long long *crash_base);
> -int crash_shrink_memory(unsigned long new_size);
> -size_t crash_get_memory_size(void);
> +int crash_shrink_memory(struct resource *res, unsigned long new_size);
> +size_t crash_get_memory_size(struct resource *res);
> void crash_free_reserved_phys_range(unsigned long begin, unsigned long end);
>
> int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 5616755..707d18e 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -925,13 +925,13 @@ void crash_kexec(struct pt_regs *regs)
> }
> }
>
> -size_t crash_get_memory_size(void)
> +size_t crash_get_memory_size(struct resource *res)
> {
> size_t size = 0;
>
> mutex_lock(&kexec_mutex);
> - if (crashk_res.end != crashk_res.start)
> - size = resource_size(&crashk_res);
> + if (res->end != res->start)
> + size = resource_size(res);
> mutex_unlock(&kexec_mutex);
> return size;
> }
> @@ -945,7 +945,7 @@ void __weak crash_free_reserved_phys_range(unsigned long begin,
> free_reserved_page(boot_pfn_to_page(addr >> PAGE_SHIFT));
> }
>
> -int crash_shrink_memory(unsigned long new_size)
> +int crash_shrink_memory(struct resource *res, unsigned long new_size)
> {
> int ret = 0;
> unsigned long start, end;
> @@ -958,8 +958,9 @@ int crash_shrink_memory(unsigned long new_size)
> ret = -ENOENT;
> goto unlock;
> }
> - start = crashk_res.start;
> - end = crashk_res.end;
> +
> + start = res->start;
> + end = res->end;
> old_size = (end == 0) ? 0 : end - start + 1;
> if (new_size >= old_size) {
> ret = (new_size == old_size) ? 0 : -EINVAL;
> @@ -975,17 +976,17 @@ int crash_shrink_memory(unsigned long new_size)
> start = roundup(start, KEXEC_CRASH_MEM_ALIGN);
> end = roundup(start + new_size, KEXEC_CRASH_MEM_ALIGN);
>
> - crash_free_reserved_phys_range(end, crashk_res.end);
> + crash_free_reserved_phys_range(end, res->end);
>
> - if ((start == end) && (crashk_res.parent != NULL))
> - release_resource(&crashk_res);
> + if ((start == end) && (res->parent != NULL))
> + release_resource(res);
>
> ram_res->start = end;
> - ram_res->end = crashk_res.end;
> + ram_res->end = res->end;
> ram_res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM;
> ram_res->name = "System RAM";
>
> - crashk_res.end = end - 1;
> + res->end = end - 1;
>
> insert_resource(&iomem_resource, ram_res);
>
> diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
> index ee1bc1b..3336fd5 100644
> --- a/kernel/ksysfs.c
> +++ b/kernel/ksysfs.c
> @@ -105,10 +105,30 @@ static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
> }
> KERNEL_ATTR_RO(kexec_crash_loaded);
>
> +static ssize_t kexec_crash_low_size_show(struct kobject *kobj,
> + struct kobj_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%zu\n", crash_get_memory_size(&crashk_low_res));
> +}
> +static ssize_t kexec_crash_low_size_store(struct kobject *kobj,
> + struct kobj_attribute *attr,
> + const char *buf, size_t count)
> +{
> + unsigned long cnt;
> + int ret;
> +
> + if (kstrtoul(buf, 0, &cnt))
> + return -EINVAL;
> +
> + ret = crash_shrink_memory(&crashk_low_res, cnt);
> + return ret < 0 ? ret : count;
> +}
> +KERNEL_ATTR_RW(kexec_crash_low_size);
> +
> static ssize_t kexec_crash_size_show(struct kobject *kobj,
> struct kobj_attribute *attr, char *buf)
> {
> - return sprintf(buf, "%zu\n", crash_get_memory_size());
> + return sprintf(buf, "%zu\n", crash_get_memory_size(&crashk_res));
> }
> static ssize_t kexec_crash_size_store(struct kobject *kobj,
> struct kobj_attribute *attr,
> @@ -120,7 +140,7 @@ static ssize_t kexec_crash_size_store(struct kobject *kobj,
> if (kstrtoul(buf, 0, &cnt))
> return -EINVAL;
>
> - ret = crash_shrink_memory(cnt);
> + ret = crash_shrink_memory(&crashk_res, cnt);
> return ret < 0 ? ret : count;
> }
> KERNEL_ATTR_RW(kexec_crash_size);
> @@ -218,6 +238,7 @@ static struct attribute * kernel_attrs[] = {
> #ifdef CONFIG_KEXEC_CORE
> &kexec_loaded_attr.attr,
> &kexec_crash_loaded_attr.attr,
> + &kexec_crash_low_size_attr.attr,
> &kexec_crash_size_attr.attr,
> &vmcoreinfo_attr.attr,
> #endif
> --
> 1.8.3.1
>
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